81413821440 has 1408 divisors, whose sum is σ = 360796032000. Its totient is φ = 17340825600.

The previous prime is 81413821439. The next prime is 81413821451. The reversal of 81413821440 is 4412831418.

It is a happy number.

81413821440 is a `hidden beast` number, since 81 + 4 + 138 + 2 + 1 + 440 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 81413821395 and 81413821404.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 806077390 + ... + 806077490.

Almost surely, 2^81413821440 is an apocalyptic number.

81413821440 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81413821440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (180398016000).

81413821440 is an abundant number, since it is smaller than the sum of its proper divisors (279382210560).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81413821440 is a wasteful number, since it uses less digits than its factorization.

81413821440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173 (or 135 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 36.

The spelling of 81413821440 in words is "eighty-one billion, four hundred thirteen million, eight hundred twenty-one thousand, four hundred forty".